Underutilized Instances in EC2 Auto Scaling Group

When workloads consistently use only a fraction of the available CPU, memory, or network capacity, there is an opportunity to downsize to smaller, less expensive instance types without sacrificing performance. Right-sizing helps balance capacity and efficiency, reducing compute spend while preserving workload stability.

EC2 instances are billed per second (60-second minimum) for Linux, Windows, RHEL, and Ubuntu Pro, and per full hour for SLES, based on instance type, operating system, and purchase model (e.g., On-Demand, Reserved Instances, Spot Instances). Larger instance types incur higher charges regardless of whether the workload fully utilizes the available resources.

• Identify Auto Scaling Groups where instances exhibit low average CPU, memory, or network utilization relative to their capacity.
• Review instance sizing in relation to historical workload peaks and scaling behavior.
• Assess whether smaller, more cost-effective instance types could support the same workload with acceptable performance.
• Evaluate launch templates (and migrate any remaining launch configurations, which are deprecated) to determine if default instance types were selected without performance optimization.
• Confirm with application and infrastructure owners that resizing aligns with performance, availability, and SLA requirements

• Evaluate smaller instance types that better match the workload's actual resource requirements.
• Update the launch template for the Auto Scaling Group to use the selected instance type, and deploy changes during a low-traffic window if needed.
• After downsizing, monitor performance metrics to ensure the workload continues to meet application and SLA expectations.
• Regularly reassess instance sizing as usage patterns evolve to maintain ongoing cost efficiency.

• Amazon EC2 Pricingaws.amazon.com
• Auto Scaling launch templatesdocs.aws.amazon.com
• Viewing EC2 Auto Scaling group recommendationsdocs.aws.amazon.com